The applicants have made two novel observations that have clear commercial potential. The first observation was the unexpected finding that methylated plasmid DNA extended the length of time a transgene is expressed in mammalian lung cells. This extension of expression is most likely due to retention of the transgene in the nucleus of transfected cells for a longer time than non-methylated plasmid DNA. The second observation is that expression of an a-1 antitrypsin transgene in lung cells has a therapeutic effect that is qualitatively different than administration of the protein. Based on these observations, the applicants propose to test the following hypotheses: 1) Selected methylation of plasmid vectors can be used to increase the efficiency of transgene delivery by extending the time of transgene expression. This same methylation can also reduce the toxicity of prokaryotic derived DNA in cells in vitro and in vivo; 2) The therapeutic potential of alpha-1 antitrypsin gene transfer as antiviral or anti-inflammatory therapy can be enhanced by delivering the gene in a selectively methylated plasmid vector. This phase I proposal is designed to extend and refine the DNA methylation observations in several cell types and in vivo. Another aim is to show, more specifically, that delivery and expression of the a-1 antitrypsin gene is enhanced and the toxicity of plasmid/cationic liposome transfection is decreased by employing a selectively methylated plasmid. In Phase II proposal the group anticipates extending the in vivo testing of the enhanced transgene vector carrying the a-1 antitrypsin gene to determine efficacy in both viral and non-infectious lung inflammatory disease as a next step toward determining clinical utility. Two eventual products are anticipated: an improved in vitro transfection reagent and a gene-based antiviral/anti- inflammatory drug. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE